Scientists use iPods, car batteries to build a frog surveillance net

Put this on your playlist: scientists at the University of Puerto Rico have developed a system to monitor wildlife in tropical rainforests, using captured audio in real time to remotely record the sounds made by animals. Using hardware that includes iPods, solar panels, and car batteries, the scientists created a network of radio-connected listening posts around the world that allows them to collect data 24 hours a day over long periods of time. The sound will help them track the effects of environmental changes—such as deforestation and climate change—on endangered species.

The system, called Arbimon (Automated Remote Biodiversity Monitoring Network), was created by a team led by Dr. Mitchel Aide and Dr. Carlos Corrada-Bravo of the University of Puerto Rico. As described in a paper published by the team in PeerJ today, Arbimon's monitoring stations use an iPod recording application to capture up to 144 one-minute audio recordings per day of animal calls. Most of the components of the monitoring stations—the iPod, the battery, a voltage converter, a preamplifier for the microphone, and a router—are in a sealed watertight case. A 50-watt solar panel powers the system and charges the battery during the day.

Enlarge/ A diagram of the components of the Arbimon monitoring network.

PeerJ

The collected audio is then transmitted over a 900MHz radio signal back to a collection base station—which can be up to 24 miles away—and is uploaded over the Internet to the team's server in Puerto Rico. Audio processing software on the server then attempts to automatically identify the species caught on the audio recordings; scientists can "teach" the system to improve its identifications or learn new species through a Web-based audio analysis application. The server can process over 100,000 recordings an hour, delivering data on the presence or absence of a species across the monitored sites.

The initial testing of the system took place in Puerto Rico and Costa Rica; data collected from the initial deployment was used to track the fluctuation in the population of the coquí llanero (Eleutherodactylus juanariveroi), an endangered species of Puerto Rican frog found only in wetlands near the former Sabana Seca Naval Base on the northern coast of Puerto Rico. Arbimon has since been deployed to monitor species in Brazil, Argentina, Hawaii, and Arizona.

The traditional data collection approach—sending biologists out into the field—"is too expensive and often results in incomplete and limited data sets," Dr. Aide said in a statement on the project. "It is impossible to maintain biologists in the field 24 hours a day throughout the year, and it is impossible to clone expert field biologists so that they can monitor various sites simultaneously."

By allowing constant sampling to be taken over long periods of time with inexpensive gear, those holes in coverage are eliminated, and "biologists can use their time to convert these data into useful information," said Dr. Corrode-Bravo. And since all of the data from recordings is archived, "biologists 20 or 50 years from now will be able to analyze these recordings with new technologies and ideas."

13 Reader Comments

What's the point of an iPod? Is there any processing being done on-site to determine what 144 minutes per day is being transmitter? Furthermore, what's with the 144 minute / 24 hour limit anyways? Seriously, if you've got the radio broadcast gear anyways, why not broadcast everything? Ok, so you don't want to run transmitter 24/7 so maybe the iPod is being used as the sampler, storage, and compression. Is lack of power limiting the amount that can be sent?

Wasn't it on Ars some time ago (2 years? 3?) that I saw an article about a guy that wanted to start a movement of people installing a simple DIY system on their roofs to automatically collect and upload sound samples of migrating birds over their houses for similar tracking? Couldn't find a link anywhere...

It was a pie tin (or something like that) acting as a collector reflecting back to a mic pointing down, iirc.

I would expect that the 144 minute limitation is due to a combination of factors, from battery conservation onsite to bandwidth conservation, to hard drive space constraints. None of these resources are unlimited, after all.

Here's what I'm curious about: They mentioned the iPods and depicted a number of other components in that slide... but are they really using Mac Mini's and XServe's in their physical infrastructure, or is that just the stock imagery that their graphics artist used to represent things?

What's the point of an iPod? Is there any processing being done on-site to determine what 144 minutes per day is being transmitter? Furthermore, what's with the 144 minute / 24 hour limit anyways? Seriously, if you've got the radio broadcast gear anyways, why not broadcast everything? Ok, so you don't want to run transmitter 24/7 so maybe the iPod is being used as the sampler, storage, and compression. Is lack of power limiting the amount that can be sent?

The prototype using off the shelf parts worked and was cheap enough, so they focused their $$'s on the other pieces of the project (processing time, signal processing algorithm, etc.).

Version 2 might be a good opportunity to do an interdisciplinary project with the EE and CS departments to design some more efficient hardware capable of recording and sending more samples on the same energy/cost budget.

Or maybe not. The article was sparse on technical details so maybe they already investigated those options and decided a custom kit was more expensive in the volumes they needed.

I love that they're using off-the-shelf consumer products to build these. They could have paid an outside agency millions of dollars to build custom contraptions, but figured making their own would work well enough and be loads cheaper. The DIY attitude is strong in this group.

Sean Gallagher / Sean is Ars Technica's IT Editor. A former Navy officer, systems administrator, and network systems integrator with 20 years of IT journalism experience, he lives and works in Baltimore, Maryland.